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Re-2: vrf Virtual serial (COM) ports

Question asked by g.nied on Mar 30, 2006
Hi Bill,
 
you are right, I tested that (char reading) long before but it takes much more time for vee to read chars than binary data (about 10 times). Moreover the changing of the EOL character does not change anything for binary reads... (seems to be a bug for me)
 
Georg
 
 

Original Message     
   processed by David InfoCenter 
Subject: 
RE: [vrf] Virtual serial (COM) ports (30-Mrz-2006 22:28)
From:    
HYPERLINK "mailto:William.Drago@L-3com.com"William.Drago@L-3com.com
To:      
HYPERLINK "mailto:vrf@agilent.com"vrf@agilent.com
 
Tis is because I want to read binary data from a serial port and VEE has that special 'feature' to stop reading data when an 0x0A byte is read. **** BTW: if somebody has a workaround, let me know *** 
 
No workaround required. Do a Read Text Byte format and specify the number of chars you want to read.
 
If the number of chars is variable or unknown, read one at a time in a loop (store them in a collector) until a timeout occurs.
 
Also, the EOL char is user defined in the instrument manager: Properties/Advanced/Direct I/O. You can make it anything you want...
 
Bill
 

Therefore I am currently experimenting with a VEE wrapper library that uses the Microsoft mscomm.ocx ActiveX control.
My serial port is connected via USB/serial converter and I just made the test that inside the running VEE program the control is 'seeing' the port if it is plugged in, not seeing it if I unplug it, and seeÃng it again if I plug it in again. This is without restarting VEE.
Perhaps that helps you.
 
Georg Nied

-----Ursprüngliche Nachricht-----
Von: David Watling [mailto:watling@IceraSemi.com]
Gesendet: Donnerstag, 30. März 2006 14:33
An: VRF
Betreff: [vrf] Virtual serial (COM) ports



Hi all,

I have to test a product which presents itself as a virtual COM port (via the PCMCIA interface).  So I plug it in to the PC, run a Vee program, get a result, and unplug it.  The only thing is, Vee (or the IO libraries) cannot handle a COM port that disappears and re-appears.  This means I have to close & re-start Vee for each device I plug in.  In a production environment, this would be highly un-satisfactory.

The IO libraries seems quite capable of handling USB devices or GPIB interfaces or TCPIP connections that come & go, just not COM ports.

 

Questions:

Is this a known bug in the IO libraries?
Is there a Vee based work-around?
Is there another work-around (eg has anyone written a wrapper dll to deal with this?)

 

Regards

 

David Watling


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